The present invention relates to charge forming systems for internal combustion engines and more particularly to an improved system for metering and vaporizing liquid fuel, and delivering it to an engine in optimum quantities.
Since the inception of the internal combustion engine, continuting efforts have been made to improve the charge forming system to achieve both the efficient and economical delivery and combustion of fuel. Of the vast sums of capital and human energy which have been expended to improve and refine the internal combustion engine, it is fair to say that the aspect of engine system which has received the most concerted attention is the charge forming system. Many types of carburetion and fuel injection systems have been devised, the vast majority of them having been abandoned as inadequate, impractical or uneconomical. Among these approaches have been numerous attempts to vaporize liquid fuel before its induction into an engine. As used herein, the term "vaporize" will be used in its true sense, in contradistinction to "atomization" as is accomplished by conventional carburetion and fuel injection systems. In this context, "atomization" denotes the dividing of a liquid into a multiplicity of small droplets, while "vaporization" will refer to the actual dissociation of the liquid molecules as, for instance, in the conversion of water to steam.
The search for improved charge forming systems has received added impetus in recent years due to the progressive constraints being placed upon vehicle emissions. In order to reduce the various pollutants normally emitted by conventional internal combustion engines, renewed efforts have been made to devise charge forming systems which burn "cleanly" as compared to previous systems. Unhappily, the systems implemented to date achieve reduced emissions at the price of decreased engine power and economy. In order to reduce emissions automotive engineers have found it necessary to retain the basic elements of the conventional charge forming system, turning to highly modified carburetors along with added accouterments such as conduits for recycling exhaust gas and means for selectively retarding ignition timing, along with thermally compensated systems for providing as lean a mixture as possible over the anticipated range of operation.
Newer, more sophisticated approaches continue to rely upon conventional carburetion or fuel injection systems which have been "programmed" to respond to various anticipated conditions in a predetermined manner. With the advent of microelectronics, it has become possible to construct an electronic system for controlling the operation of carburetors or fuel injectors by synthesizing signals representing the desired system operation, in response to sensed stimuli. However, all of the foregoing systems continue to be constructed about a basically conventional charge forming means. Due to the superimposing of control stages, sensors, and pre-programmed electronic controllers the systems have become increasingly complex and expensive. Moreover, as the number of components of the system increases, the inherent reliability of the system necessarily decreases.
Still another feature which has been attempted to be implemented into charge forming systems for spark ignited internal combustion engines is the capability of adapting to various diverse sorts of liquid fuels. Since for each fuel a particular fuel/air ratio must be maintained by the charge forming system over the entire range of engine operation, it has been found difficult to adapt prior art systems to receive various, diverse sorts of liquid fuels.
Accordingly, it will be understood from the foregoing that there is a continuing need for a charge forming system for an internal combustion engine which is readily adaptable for use with various sorts of liquid fuels, and for a system which provides optimal engine efficiency and performance over an intended operating range, while minimizing the emission of pollutants from the engine.
It is therefore an object of the present invention to provide an improved charge forming system for an internal combustion engine with superior fuel distribution characteristics.
It is another object of the present invention to provide an improved charge forming system for metering and vaporizing a liquid fuel.
Another object of the invention is to provide an improved fuel metering system which is readily adaptable for use with diverse liquid fuels.
Still another object of the present invention is to provide a system for implementing the formation of stratified charges in an internal combustion engine wherein a leaner-than-stoichiometric strata of the charge is derived from vaporized liquid fuel.
Yet another object of the invention is to provide means for automatically maintaining optimal proportions of vaporized fuel and air in an internal combustion engine.
Another object is to provide a charge forming system which achieves a significant diminution in pollutant output.